In displays, since organic light emitting diodes (OLEDs) have various merits, such as self-luminescence, high brightness, low response time and the like, as compared with liquid crystal displays (LCDs), many studies have focused on OLEDs.
OLEDs include an organic light emitting material. Typically, the organic light emitting material is applied by deposition. However, deposition has a problem of difficult formation of a uniform organic light emitting material layer.
Recently, thermal transfer is used in the art. In thermal transfer, when a transfer film includes a photothermal conversion layer and an organic light emitting material layer therein and is subjected to light irradiation using a laser or the like, a material included in the photothermal conversion layer absorbs light and emits heat, thereby transferring the organic light emitting material layer onto a substrate. Thermal transfer facilitates formation of the uniform organic light emitting material layer, as compared with deposition.
Typically, carbon black is used as a light-absorbing material for the photothermal conversion layer of the transfer film. Carbon black has difficulty in transmitting visible light and securing transparency of a film, thereby making it difficult to achieve accurate alignment of the transfer film with the substrate.
In the related art, Korean Patent Publication No. 10-2011-0069708 (publication date: Jun. 23, 2011) discloses a photothermal conversion sheet, an organic electroluminescent material sheet using the same, and a method of manufacturing an organic electroluminescent device.